P06CB code meaning
Cylinder 7 Glow Plug Incorrect
Powertrain system Generic code P06xx codes Check engine light
What P06CB means
A glow plug has no identification; the control unit recognises its type only from its electrical behaviour – cold resistance at switch-on and how resistance rises during heating (R = U/I). A Beru patent describes how steel and ceramic plugs are told apart this way so the right heating profile is used and a wrong or mixed type is reported. A low-voltage plug on an 11 V control burns out, an 11 V plug on a low-voltage control glows too weakly. GM uses 'incorrect' for any resistance outside the window: the 2025 diesels check 0.22–2.00 Ω (15 of 25 samples, two trips), the L5P glow module a ramp-dependent window. P06CB reports this for cylinder 7. GM fixed false codes on 2020 HD and 1500 diesels by reprogramming.
P06CB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P06CB
- Check engine and glow plug lamp
- Harder cold start or white smoke
- Possibly plug burnt out (low-voltage plug on 11 V control)
- Code after replacing plugs
Common causes of P06CB
- Most likelyWrong glow plug type fitted in cylinder 7 (steel/ceramic, voltage rating)
- PossiblePlug resistance drifted (ageing, damage)
- PossibleGlow module software or check during cranking (false report)
- Less likelyContact resistance at the plug connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Glow plugGlow plug control module
What each part of P06CB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| CB | The exact fault in that area. |
What to do next
- Note P06CB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P06CB
What does P06CB mean?
P06CB means "Cylinder 7 Glow Plug Incorrect". A glow plug has no identification; the control unit recognises its type only from its electrical behaviour – cold resistance at switch-on and how resistance rises during heating (R = U/I). It is a generic code, so it means the same on every make.
Is it safe to drive with P06CB?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P06CB fail an emissions test?
Yes, it can. P06CB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P06CB to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P06CB clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.